Thermal cut-out.



J, SACHS.

THERMAL GUT-OUT.

APPLICATION FILED MAYfi, 1908.

1 1 4;, 098 Patented Jan. 9, 1912.

2 SHEETSSHEET 2.

A zM/A UNITED STATES PTENT OFFICE JOSEPH SACHS, OF HARTFORD,CONNECTICUT, ASSIGNOR. To THE SACHS COMPANY, OF HARTFORD, CONNECTICUT, ACORPORATION OF CONNECTICUT.

THERMAL GUT-OUT.

, cut, have invented certain new and useful Improvements in Thermal Cut-Outs, of which the following is a full, clear, and exact description.

My invention relates to improvements in thermal cut-outs for electriccircuits.

,Fuses have been described in which a strip was surrounded by a thinlayer of material applied directly to the surface of the strip in theform of a paste and hardened, and then secured in a tubular casingprovided with proper terminals electrically connected to the fuse strip.In other instances, an immediately surrounding loose material has beenheld to the strip by a tubular sheath or interior casing surrounded inturn by an external casing having terminals to which the strip waselectrically connected. The constructions referred to in this paragraphare described in a patent granted to me October 24th, 1899, No.(335,395.

In order to more advantageously use a loose filling in the inner tubesor casings referred to in the last paragraph, it has been suggested thatthat tube be provided with end closures so as to produce a. cartridge,the casing and closures of which would keep the loose filling about thestrip. This cartridge construction placed Within a second casing isdescribed and claimed in my Patent No. 737,282, granted August 25, 1903.

Fuses have also been patented in which the strip was jacketed with aWoven asbestos tube so that the strip and tube were as a combinedstructure inserted in a box or casing. the whole constituting aninclosed fuse with a porous jacket as distinguished from a fusesurrounded by a loose porous material, inclosed in a non-porous sheath.This asbestos sleeve structure is described in patent to McCullOch, No.550,638. In all these devices employing inner tubes, with or Withoutclosures for such inner tubes, the expense of the construction has beena great objection, furthermore a large portion of the space within theouter casing has not been utilized. Moreover, there has been nosatisfactory means for ascertaining what the Specification of LettersPatent.

Application filed May 5, 1908.

Patented Jan. 9, 1912.

Serial NO. 430,976.

condition Of the fuse strip may be by an inspection from without theouter Casing. In the structures where an adhering substance Was applieddirectly to the fuse strip it was a mere coating and not a filling orprovided with chambers or interstices permitting the ready dispersion ofthe gases and metal of the fuse When molten, and did not fill theexternal casing. In the asbestos sleeve construction there was nofilling, properly speaking, but simply a sleeve which occupied but asmall portion of an inclosing casing, the gases discharging into the airspace surrounding the sleeve. On account of the expense and littleadvantage of such devices the inclosed fuses of commerce are now and fora long time have been constructed without employing an inner cartridge,and Without employing any inner sheath for holding the filling about thestrip and Without hav ing the strip either jacketed orcoated, but

so that the outer casing holds a loose filling.

material about the strip and so as to be ready for use without doingmore than to make connection with line terminals. That is, the inclosedfuses of commerce have been constructed with a fusible conductorsurrounded by a loose insulating filling material held'abontsaidconductor by a tubular casing, the end openings of which were closed byconducting ferrules or end caps, which in themselves acted as theexternal contacts or from which the Contact blades projected. Thiscombination of parts formed a composite self-containedcartridgestructure, and was manufactured, sold and used as a whole to be usedWithout any additional casing and could only be replaced by an entirelynew and similarly complete device whenever the fuse strip Was blown orruptured by an excess of current. These cartridges have been inclosed infuse plugs, but except in fuse plugs they have not been introduced toany extent into commercial use in connection with other externalcasings. As the tubular casing, ferrules and external contacts form themajor portion of the mate rial cost of such incloscd fuses orcart-ridges, particularly in the larger sizes, the replacing of suchblown or ruptured inclosed fuses of this type is necessarily expensive.As such complete structures are manufactured for a definite carryingcapacity and cannot be readily changed by she user or seller, itisnecessa y that he 8&11/ a large variety of the p *seno form of completeinclosed fuses of drier ens ampere capacities for a certain size blockhe desired to prepared to i ery the current carrying capacity of hisinciosed fuse o out apofanee. This consequently nccessit Les aexpenditure for siflo'clr iiiciosed fuses, which. could be eliminated ifa cheap refill or reioad were provided the tubular casing, ferrules andexternal consaets were properly constructed, so llllQV could he usedrepeatedly if the disruptedsirip its arc-dissipatiag envirouinen'fiwhich held around it within. om tuhnia asing could. be easily andiyirenewe One oftheobjecos of my invention is to satisfactorilyaeooroplsi. this resuit, and to that end 1' provide iniegrally combinedreloa or reliil onsistin of: the fuse stri'o surrounded by s oohei garc-dissi- Dating filiing substance so that these two elements or partsare in: themselves cora unit and will. hold Wiill addinionsl means, alsosuitable easing, hex, sube, or other e. .ernal gorotecfior inclosingstruc l which eu oe refills or reioads can be ream i which theysuhstaniaily fill, provided whereby the tern strip of the reload orquickly and securely eonneeiv nai. contacts ehe ins i casing see 'lyclosed preferably 1y the iisuring she proper e the fuse sizrip hetweei'it by the operation of casing so that i memberineu pressures d lisruption01.. structure ine ass? vsingthe ably casing closu e um. Lu with the pand. replaceable r e: annals are whole we now in use casjacketed41151.2) 4. one 32 .cwisno the reloed or refill and in the preferredform entirely surround the indicating means bodying n y invention. Fig.2 shows in plan a reload or refill with the terminals of she fuse stripextending at its ends. This reload has located upon it an indicatorform" ing a composite pare thereof. Fig. 3 shows a partial view with thecasing in longitudinal section on the line g -g Fig. 4., an end view ofthe fuse of Fig. 1, the plate being removed. Fig. 5 is a sec iioni'z-alren through Fig. 1 at the line 2e. F 6 shows an end view of therefill shown in 2. 7 shows in section a fuse plug embodying myinvention. Figs. 8 and 9, 10 and 11 show reloads withnnodified forms ofterminals at their ends and corresponding ca ing terminals. Figs. 12, 13and 14 show a LilSG block embodying my invention, Fio'.

being a side elevation partly in section,

Fig. 13 a portion of the block with one of the covers removed, and Fig.1 an end eleration.

Referring more particularly to the drawings, A is a casing, preferablytubular and constructed of fiber or other suitable insulating" material.13-13 are counterpart metallic end caps or casing terminals fitting overthe ends of said. casing and held thereto by suit-able fasteningdevices, the fastening device shown consisting of a screw C en aging abayonet slot 1) in each of the end The screws G preferably engage withnuts or groniets (,Z sunken in the tubular easing so e0 furnish a strongscrewihread, and the ends of the screws may be headed eveon the insideof the casing so that they mot h entirely removed therefrom. .ihe screwsengaging with fihebeyw ei; slois constitute preferred form for securingthe caps in position.

suitable means, however, may be employed for accomplishi this purpose.When end closures are used one of them at least should be removable. inthe large sized fuses the end. cans are nrovided with contactblades "*l;ies B are omitted as consliaiul'e both end Any other mg E, through whichevidences of the condition of the refill can be detected.

Means are provided for securing the terminals of the fusible strip inelectrical engagement with the end caps, the preferred form being thatof Figs. .1-4 and consistin" of a clamping device consisting of 9. sp itplug having two parts F-F and a nut G. The parts F -F each have aflaring end HI-I' which engages a conical bearing surface I on theinside of the cap. The

split plug has a hole through it concentric with the end of the fusestrip terminal.

\Vhen the refill is secured. in place the round terminals project intothe holes in the clamps, and the nuts are screwed down so as to draw thesplit plug members FF into close clamping engagement with the terminals,thus securing an excellent electrical continuity between the fuseterminals and the end caps and the contact blades B attached thereto ifsuch contact blades are used. The caps when clamped to the fusiblewconductor terminals are by such clamping fixed in position relativelyto one another and to the casing. The nuts G are screwed on by a righthand movement and the caps are turned by a movement in the samedirection to seat the shanks of the screws C against the innermost endsof the bayonet slots. This seating of the screws C and the screwing ofthe nuts G can thus be done by the same movement or operation.

The refill or reload consists of a fusible conductor J which, as shown,is connected between terminals or connections K-K of copper or othermetal harder and less fusible than the fusible conductor J. Theseterminals or connections are shown in Figs. 1, 2, 3, 4t and 6 as roundwires, riveted, soldered or otherwise connected to the ends of thefusible conductor, and in Figs. 9, 10 and 11 as flcxibk strips of copperor the like. The

fuse strip and the inner ends of the terminals are surrounded by acohering jacket L, which consists of insulating material. I prefer touse ,for this purpose granular earthy substances of the calcium group,which are combined by means of suitable binders toproducc an integralcellular-multichambered spongy or porous mass, which 7 mass 15 molded,compressed or otherwise formed and held around and in contact withthc'fusc strip so as to form therewith the jacketed strip or reload. Asuitable way of making this cellular jacket is to combine coarselyground set plastcrof-paris with a solution of silicate of soda,'whichforms therewith a pasty mass and at the right consistency can be cast ormolded around the strip. It may also be formed by holding the groundmaterial about the fusible conductor in 'a mold and pouring silicate ofsoda through it while thus held. The surpreferably provided with awindow or open-,

plus silicate of soda is permitted to drain off leaving intersticesbetween the granules or particles of the plastcr-of-paris which are heldtogether by the binding and chcni'r cal action of the silicate of soda,forming a. cohcring cellular jackct adhering to the fuse strip so as tobe integral with the fuse strip. Although a suitable jacket may be madein this way, various faitures of my invention may be embodied withoutthe use of ajacket which adheres to the strip. I therefore do not limitmyself to such an adhering or integral jacket or the stated chemicalelements, since they are not essential to form the cellular structure ofmy reload jacket.

,It will be noted that the jacket L is molded so as to entirely incloseand surround the fuse strip J and also a small portion of the inner endsof the terminals or connections KK between which the fuse strip J isconnected. It is al o preferably of such size as to nearly fill thecasing, but not to bind therein when being inserted or removed.

Although I have shown terminals lC-K of metal harder than the fuse stripand not integral therewith, this not of essence, since other well knownforms of strip and terminals can be used.

In order that the condition of the reload may be apparent on theexterior of the jacket, and'if necessary on the exterior of the externalcasing surroimding the jacket or cohering filling, I provide indicatingmeans which in Figs. 1, 2, 5 and 6 are shown as an indicating compoundor connection M located and electrically connected between the ends ofconductors N--N which at their outer ends are electrically jointed orconnected to the terminals K-K. This indicating connection M is composedof a conducting material such as graphite with which has beenincorporated an easily ignitible or heat affected material, such as gunpowder, or picric acid. The combined substances are put into plastic orfluid condition, and in this state the compound is placed in positionbetween the ends of the conductois N--N. These ends are previouslyhooked over from the under side of a perforated sticker or label (l, sothat the secured against turning by being slightly I embedded in thejacket, or by solder, or I both, and extends beyond the periphery of therefilkso as to engage a notch or recess l?" in one end of the tubularcasing. This arm or projection has a fixed or definite sition relativelyto the indicator c )Ollilfl.

The casing is provided with a window or aperture E, which is at a properdistance w from the notch P so that the arm or projection P when withinthe notch P will cause the indicator compound to be in the properposition relatively to the window or aperture.

The jacket L after it is dried is preferably coated with one or morecoats of as phaltum or similar heat-resisting varnish to give it afinish and increase its coherency. This should preferably be appliedafter the indicator conductors have been connected to the fuseterminals.The inner end surface of the caps is covered with a felted asbestoswasher ll,j held in place by the flaring upset portion that forms theconical recess T. This washer covers apertures or vents T in the casingterminals.

In using my reload-able inclosed fuse, it is necessary simply to takethe reload consisting of the combined strip and jacket, and insert itinto the tubular casing througlr the opening at either end, one cap onlybe- .ing removed. After being positioned therein, the removed cap isreplaced and having a screw-threaded opening engagin turned so as to besecured by the bayonet joint and the nuts G screwed down so as to clampthe fuse terminals it. to the It is desirable that the reload be soinserted that the indicating connection be removed from, though inproximity to, the aperture in the casing, and it will be noted that itis not possible to insert the reload otherwise on account of theregistration p'" l? fitting in a recess 1 in the casing.

v The indicator compound is therefore entirely surrounded.

45 by the casing and there is, therefore, no one posed conductingelement at the opening so that it is not possible to have any Flash orare at this opening, due to the rupture of any conducting element atthat point, as

would be the case if a current carrying conductor were located directlybeneath the hole or aperture in the casing. An exposed flash attheopening would be a source of danger, since it liable to ignite anyexplosive gases \vl Ich may be present, or any easily ignitablc materialwhich may be at" hand, and the presence of an exposedccnductor at theopening is undesirable in that it enables an GlBCdllQ connection to bemade at that point.

' in operation, an excess of current go st through the fusible stripwill 3' ing it to rupture, and the prodir disrupted strip will bedissipated I 1 v the interstices of the cellular or on up the arc. Assoon as the use been thus ruptured, the current 7 then pass through theindicating con 3B, which. is connected in shunt around. strip. Thisconnection being of Very ni h resistance, normally does not carryappreciable current. "W hen heated by the passage of current after thefuse strip is, blown, the indicating connection will be ignited orotherwise affected, so that the products of such heating, ignition orother change, will be of a nature to discolor the surface of the labelin proximity thereto. This discoloration will be visible from the anexterior of the external casing through the aperture, and thereby thecondition of the reload will be seen. The folded flap 6'. serves todirect'these products toward the aperture E soas to insure that theportion of the jacket beneath the aperture shall be subjected to them. v

Fig. 8 shows the refill with another form f terminal and indicatingdevice, and. also other means of fastening the cap upon the as casingand electricallyconnecting the-fuse strip thereto. In this form the fusestrip is provided with screw-threaded terminals Q; over eachpt whichispassed a cap It,

said terminal screw-threads. The cscrewed on to a terminal Q, and asetis then screwed upon the screw-tin... portion Qholding the together.a contact blade 8 free from the cap may made integral with this nut, tle thread i ing sutiiciently fine so the blades at the ends can be placedin the same plane. cap is secured to the casing by a screw passingdirectly through a hole in the cap. An indicating connection Ml8QiE'lC.. connected by conductors N-l*l as in Fig and acting in thesame manner, is attached to and earricd'by the jacket of the refill andits strip. Another means of securing the e it to the casingandelectrically COHH'EL the use strip thereto is shown in ll, 10 and 11. Tnthis construction the fuse strip terminal of thin :tleiriblt metal,preferably copper. It is bentlI" so as to come in direct contact withthe terior surface of the casing- A. The nal of the fuse strip isprovided with. a slot a which is slipped aroundthe shank of the screw V.The cap B with its bayonetjoinbW is then slipped on and turned in .iil

place and the screw set so as to hold the p in place and clamp itagainst the unnal U.

in. 7 shows my invention in a fuse plug. in this constru cn'ibod oticn, 1. the refill, consisting of a j: 4 strip at h as shown in Fig.but horter and. w out an indicator, this latter feature not beed by acohering integral cellular nally manifesting the condition of thefusible conductor through the aperture, and means for positioning thereload in the casing so that the indicator is entirely inclosed andcompletely surrounded by the casing and out of alinenient with saidaperture.

9. In an inclosed fuse, the combination of a tubular casing ofinsulating material, an indicator hole in said casing, end closures andcircuit. connecting contacts at the end of the casing, a fusibleconductor surroundfilling material forming together a removable reload,a shunt circuit indicator attached to and forming a part of said reload,said indicater being upon the outer surface of the filling material,means 'coacting with the end closures and the terminals of the fusibleconductor projecting from the ends of the reload for detachably holdingthe reload within the casing, and electrically connecting the fusibleconductor to the contacts,

and registration means for locating the reload in the casing so that theshunt indider of cellular structure having a multitude of intersticesfor receiving the products of the fuse strip When disrupted, a fusibleconductor Within the filling with terminals extending beyond the ends ofthe cylinder, and

an indicator mounted upon said cylinder;-

11. A filling for inclosed fuses composed of granular non-conductingmaterlal, in combination with a non-conducting blnding agent holding thesame together in the form. v

of a cohering cellular mass.

JUSEPH SACHS.

W'itnesses: g 7

LILLIAN S. James, H. B, Baownntn

